vendredi 19 octobre 2012

Video above: A study of 544 star-forming galaxies observed by the Keck and Hubble telescopes shows that disk galaxies like our own Milky Way unexpectedly reached their current state long after much of the universe's star formation had ceased. Over the past 8 billion years, the galaxies lose chaotic motions and spin faster as they develop into settled disk galaxies. Credit: NASA's Goddard Space Flight Center.

A comprehensive study of hundreds of galaxies observed by the Keck telescopes in Hawaii and NASA's Hubble Space Telescope has revealed an unexpected pattern of change that extends back 8 billion years, or more than half the age of the universe.

"Astronomers thought disk galaxies in the nearby universe had settled into their present form by about 8 billion years ago, with little additional development since," said Susan Kassin, an astronomer at NASA's Goddard Space Flight Center in Greenbelt, Md., and the study's lead researcher. "The trend we've observed instead shows the opposite, that galaxies were steadily changing over this time period."

Today, star-forming galaxies take the form of orderly disk-shaped systems, such as the Andromeda Galaxy or the Milky Way, where rotation dominates over other internal motions. The most distant blue galaxies in the study tend to be very different, exhibiting disorganized motions in multiple directions. There is a steady shift toward greater organization to the present time as the disorganized motions dissipate and rotation speeds increase. These galaxies are gradually settling into well-behaved disks.

Graphic above: This plot shows the fractions of settled disk galaxies in four time spans, each about 3 billion years long. There is a steady shift toward higher percentages of settled galaxies closer to the present time. At any given time, the most massive galaxies are the most settled. More distant and less massive galaxies on average exhibit more disorganized internal motions, with gas moving in multiple directions, and slower rotation speeds. Credit: NASA's Goddard Space Flight Center.

Blue galaxies -- their color indicates stars are forming within them -- show less disorganized motions and ever-faster rotation speeds the closer they are observed to the present. This trend holds true for galaxies of all masses, but the most massive systems always show the highest level of organization.

Researchers say the distant blue galaxies they studied are gradually transforming into rotating disk galaxies like our own Milky Way.

"Previous studies removed galaxies that did not look like the well-ordered rotating disks now common in the universe today," said co-author Benjamin Weiner, an astronomer at the University of Arizona in Tucson. "By neglecting them, these studies examined only those rare galaxies in the distant universe that are well-behaved and concluded that galaxies didn't change."

Rather than limit their sample to certain galaxy types, the researchers instead looked at all galaxies with emission lines bright enough to be used for determining internal motions. Emission lines are the discrete wavelengths of radiation characteristically emitted by the gas within a galaxy. They are revealed when a galaxy's light is separated into its component colors. These emission lines also carry information about the galaxy's internal motions and distance.

Simulations such as this will help astronomers better understand the new findings in galaxy evolution. It tracks the development of a single disk galaxy from shortly after the Big Bang to the present day. Colors reveal old stars (red), young stars (white and bright blue) and the distribution of gas density (pale blue); the view is 300,000 light-years across. Credit: F. Governato and T. Quinn (Univ. of Washington), A. Brooks (Univ. of Wisconsin, Madison), and J. Wadsley (McMaster Univ.).

The team studied a sample of 544 blue galaxies from the Deep Extragalactic Evolutionary Probe 2 (DEEP2) Redshift Survey, a project that employs Hubble and the twin 10-meter telescopes at the W. M. Keck Observatory in Hawaii. Located between 2 billion and 8 billion light-years away, the galaxies have stellar masses ranging from about 0.3 percent to 100 percent of the mass of our home galaxy.

A paper describing these findings will be published Oct. 20 in The Astrophysical Journal.

The Milky Way galaxy must have gone through the same rough-and-tumble evolution as the galaxies in the DEEP2 sample, and gradually settled into its present state as the sun and solar system were being formed.

In the past 8 billion years, the number of mergers between galaxies large and small has decreased sharply. So has the overall rate of star formation and disruptions of supernova explosions associated with star formation. Scientists speculate these factors may play a role in creating the evolutionary trend they observe.

Now that astronomers see this pattern, they can adjust computer simulations of galaxy evolution until these models are able to replicate the observed trend. This will guide scientists to the physical processes most responsible for it.

The DEEP2 survey is led by Lick Observatory at the University of California at Santa Cruz in collaboration with the University of California at Berkeley, the University of Hawaii at Manoa, Johns Hopkins University in Baltimore, Md., the University of Chicago and the California Institute of Technology in Pasadena.

The Hubble Space Telescope is a project of international cooperation between NASA and the European Space Agency. NASA's Goddard Space Flight Center in Greenbelt, Md., manages the telescope. The Space Telescope Science Institute (STScI) in Baltimore, Md., conducts Hubble science operations. STScI is operated by the Association of Universities for Research in Astronomy, Inc. in Washington.

Studying planets around other stars will be the focus of the new small Science Programme mission, Cheops, ESA announced today. Its launch is expected in 2017.

Cheops – for CHaracterising ExOPlanets Satellite – will target nearby, bright stars already known to have planets orbiting around them.

Through high-precision monitoring of the star’s brightness, scientists will search for the telltale signs of a ‘transit’ as a planet passes briefly across its face.

In turn, this will allow an accurate measurement of the radius of the planet. For those planets with a known mass, the density will be revealed, providing an indication of the internal structure.

Artist impression of Cheops

These key parameters will help scientists to understand the formation of planets from a few times the mass of the Earth – ‘super-Earths’ – up to Neptune-sized worlds.

It will also identify planets with significant atmospheres and constrain the migration of planets during the formation and evolution of their parent systems.

Cheops is the first of a possible new class of small missions to be developed as part of ESA’s Science Programme.

“By concentrating on specific known exoplanet host stars, Cheops will enable scientists to conduct comparative studies of planets down to the mass of Earth with a precision that simply cannot be achieved from the ground,” said Professor Alvaro Giménez-Cañete, ESA Director of Science and Robotic Exploration.

“The mission was selected from 26 proposals submitted in response to the Call for Small Missions in March, highlighting the strong interest of the scientific community in dedicated, quick-turnaround missions focusing on key open issues in space science.”

Planet transit in front of a star

Possible future small missions in the Science Programme should be low cost and rapidly developed, in order to offer greater flexibility in response to new ideas from the scientific community.

With a dedicated science focus, they would provide a natural complement to the broader Medium- and Large-class missions of ESA’s Science Programme.

Cheops will be implemented as a partnership between ESA and Switzerland, with a number of other ESA Member States delivering substantial contributions.

“This continues the 40-year success story of Swiss scientists and industry at the forefront of space science,” said Professor Willy Benz, Center for Space and Habitability at the University of Bern.

The mission will also provide unique targets for more detailed studies of exoplanet atmospheres by the next generation of telescopes now being built, such as the ground-based European Extremely Large Telescope and the NASA/ESA/CSA James Webb Space Telescope.

Cheops will operate in a Sun-synchronous low-Earth orbit at an altitude of 800 km. It has a planned mission lifetime of 3.5 years and part of the observing time will be open to the wider scientific community.

jeudi 18 octobre 2012

Image above: Three bite marks left in the Martian ground by the scoop on the robotic
arm of NASA's Mars rover Curiosity are visible in this image taken by
the rover's right Navigation Camera during the mission's 69th Martian
day, or sol (Oct. 15, 2012). Image Credit: NASA/JPL-Caltech/MSSS.

NASA's Mars rover Curiosity has ingested its first solid sample into an analytical instrument inside the rover, a capability at the core of the two-year mission.

The rover's Chemistry and Mineralogy (CheMin) instrument is analyzing this sample to determine what minerals it contains.

"We are crossing a significant threshold for this mission by using CheMin on its first sample," said Curiosity's project scientist, John Grotzinger of the California Institute of Technology in Pasadena. "This instrument gives us a more definitive mineral-identifying method than ever before used on Mars: X-ray diffraction. Confidently identifying minerals is important because minerals record the environmental conditions under which they form."

Image above: The robotic arm on NASA's Mars rover Curiosity delivered a sample of Martian soil to the rover's observation tray for the first time during the mission's 70th Martian day, or sol (Oct. 16, 2012). Image Credit: NASA/JPL-Caltech/MSSS.

The sample is a sieved portion -- about as much material as in a baby aspirin -- from the third scoop collected by Curiosity as a windblown patch of dusty sand called "Rocknest." The rover's robotic arm delivered the sample to CheMin's opened inlet funnel on the rover's deck on Oct. 17.

The previous day, the rover shook the scooped material inside sample-processing chambers to scrub internal surfaces of any residue carried from Earth. One earlier scoopful was also used for cleaning. Additional repetitions of this cleaning method will be used before delivery of a future sample to the rover's other internal analytic instrument, the Sample Analysis at Mars investigation, which studies samples' chemistry.

Various small bits of light-toned material on the ground at Rocknest have affected the rover's activities in the past several days. One piece about half an inch (1.3 centimeters) long was noticed on Oct. 7. The rover team postponed use of the robotic arm for two days while investigating this object, and assessed it to be debris from the spacecraft.

This image shows part of the small pit or bite created when NASA's Mars rover Curiosity collected its second scoop of Martian soil at a sandy patch called "Rocknest." Image credit: NASA/JPL-Caltech/MSSS.

Images taken after Curiosity collected its second scoop of Rocknest material on Oct. 12 showed smaller bits of light-toned material in the hole dug by the scooping action. This led to discarding that scoopful rather than using it to scrub the processing mechanisms. Scientists assess these smaller, bright particles to be native Martian material, not from the spacecraft.

"We plan to learn more both about the spacecraft material and about the smaller, bright particles," said Curiosity Project Manager Richard Cook of NASA's Jet Propulsion Laboratory, Pasadena. "We will finish determining whether the spacecraft material warrants concern during future operations. The native Mars particles become fodder for the mission's scientific studies."

During a two-year prime mission, researchers are using Curiosity's 10 instruments to assess whether the study area has ever offered environmental conditions favorable for microbial life. JPL, a division of Caltech, manages the project and built Curiosity. For more about Curiosity, visit: http://www.nasa.gov/msl and http://mars.jpl.nasa.gov/msl .

With all of the excitement of the Mars Curiosity landing, many are looking to move from robots to humans for exploration beyond Earth's orbit. Keeping in mind the Seven Minutes of Terror, just imagine the nail-biting moments of putting people into the harsh environment of space far from their home planet. Taking the guess work out of long-duration exploration, however, is one of the benefits of the International Space Station. This orbiting laboratory serves as a test bed for technology and helps researchers understand how to prepare for extended trips in space.

"The space station is so valuable in this effort because it provides so much of what encompasses a long-duration transit mission, but with the convenience and lower risk of being located in low Earth orbit," said George Nelson, manager of International Space Station Technology Demonstration with NASA.

Image above: NASA astronaut Andrew Feustel, STS-134 mission specialist, installs the Materials on International Space Station Experiment – 8, or MISSE-8, hardware. MISSE-8 is a test bed for materials and computing elements attached to the outside of the International Space Station. (NASA).

Communications is one of the concerns that the space station can assist with, as delays of radio and telemetry information between the crew and mission control increase the further a vehicle gets from the Earth. Current space station operations rely on fast and almost continuous voice, data, command, and telemetry transmissions with controllers on the ground. Mars missions, however, could have up to a 20-minute delay in sending and receiving data. While the timing varies from destination to destination, the approach to preparing for continued operations is the same.

Astronauts need proven procedures for how to operate independently from mission control. Aboard station, the crew practices countermeasures for delays by operating certain activities with self-enforced lapses in communications. For instance, in the summer of 2012 astronauts successfully performed preventative maintenance on the COLBERT on-orbit treadmill while purposely not speaking with flight controllers. This is a step in the right direction for creating autonomy.

"The operations community has recently worked to revise many space station crew procedures to eliminate the need for communication with the ground," said Nelson. "We are currently testing some of these revised procedures on station to verify that they can be performed effectively. In addition, we are attempting new procedure formats, uplinked videos for instance, that may be even more effective."

The Materials International Space Station Experiment, or MISSE, series of investigations also helps with the development of protective materials. These advances may safeguard future vehicles and crew against things like radiation, extreme temperatures, atomic oxygen, and sunlight. The samples fly for set durations of time in direct contact with the space environment, prior to returning to the ground for testing.

Maintaining a safe living area in space requires technology advances not only for vehicle exteriors, but for inside as well. Researchers and engineers continually look to find better ways to provide a crew with clean, sustainable air and water. For instance, aboard the station the Environmental Control and Life Support System, or ECLSS, advances scientific understanding and design elements to improve future closed-loop life support systems.

Image above: NASA's Hubble Space Telescope took this close-up of Mars, the Red Planet, when it was just 34,648,840 miles (55,760,220 kilometers) away from Earth. Mars is just one of the potential destinations for long duration exploration that may benefit from the use of the International Space Station as a technology test bed. (NASA).

Other benefits of this on-orbit testing include greater efficiency, design improvements to reduce equipment mass, and accelerated technology developments thanks to longer trial periods in microgravity. One new life support technology currently undergoing testing aboard station is the Amine Swingbed. This equipment is designed to remove carbon dioxide from the living space inside the modules of the orbiting laboratory. When humans take in oxygen, they breathe out carbon dioxide, which needs to be scrubbed from the air to ensure continued crew health. This system is more compact and runs on less power than its predecessors.

International Space Station (ISS). (NASA)

"Testing of various life support systems is an ideal use of the space station," said Nelson. "Reliability of these systems on long distance/duration missions is paramount. We can verify design reliability in the microgravity environment by using them on station without any mission or crew risk, since the existing systems are always available."

The Curiosity of humanity may have reached Mars first, but it is our continued innovations and testing, like those done aboard the space station, that will help people follow the lander to the Red Planet and beyond.

mercredi 17 octobre 2012

This image contributed to an interpretation by NASA's Mars rover Curiosity science team that some of the bright particles on the ground near the rover are native Martian material. Other light-toned material nearby (see PIA16230) has been assessed as small debris from the spacecraft. Image Credit: NASA/JPL-Caltech/MSSS.

Commands will be sent to Curiosity today instructing the rover to collect a third scoop of soil from the "Rocknest" site of windblown Martian sand and dust. Pending evaluation of this Sol 69 (Oct. 15, 2012) scooping, a sample from the scoopful is planned as the first sample for delivery -- later this week -- to one of the rover's internal analytical instruments, the Chemistry and Mineralogy (CheMin) instrument. A later scoopful will become the first solid sample for delivery to the rover's other internal analytical instrument, the Sample Analysis at Mars (SAM) instrument.

This image from the Mars Hand Lens Imager (MAHLI) camera on NASA's Mars rover Curiosity shows a small bright object on the ground beside the rover at the "Rocknest" site. The object is just below the center of this image. It is about half an inch (1.3 centimeters) long. The rover team has assessed this object as debris from the spacecraft, possibly from the events of landing on Mars. Image Credit: NASA/JPL-Caltech/MSSS.

The rover's second scoopful, collected on Sol 66 (Oct. 12), was intentionally discarded on Sol 67 due to concern about particles of bright material seen in the hole dug by the scooping. Other small pieces of bright material in the Rocknest area have been assessed as debris from the spacecraft. The science team did not want to put spacecraft material into the rover's sample-processing mechanisms. Confidence for going ahead with the third scooping was based on new assessment that other bright particles in the area are native Martian material. One factor in that consideration is seeing some bright particles embedded in clods of Martian soil. Further investigations of the bright particles are planned, including some imaging in the Sol 69 plan.

Mars Science Laboratory (MSL). Image Credit: NASA/JPL-Caltech

Sol 69, in Mars local mean solar time at Gale Crater, will end at 5:01 a.m. Oct. 16, PDT (8:01 a.m., EDT).

Here's the Scoop!

Video above: Curiosity shakes up a scoopful of dirt, dusts off the sampling system and investigates a shiny object on the surface of Mars. Credit: NASA/JPL-Caltech.

The first direct detection of radioactive titanium associated with supernova remnant 1987A has been made by ESA’s Integral space observatory. The radioactive decay has likely been powering the glowing remnant around the exploded star for the last 20 years.

ESA’s Integral space observatory in orbit

Stars are like nuclear furnaces, continuously fusing hydrogen into helium in their cores. When stars greater than eight times the mass of our Sun exhaust their hydrogen fuel, the star collapses. This may generate temperatures high enough to create much heavier elements by fusion, such as titanium, iron, cobalt and nickel.

After the collapse, the star rebounds and a spectacular supernova explosion results, with these constituent elements flung into space.

Supernova remnant 1987A

Supernovae can shine as brightly as entire galaxies for a very brief time thanks to the enormous amount of energy released in the explosion.

After the initial flash has faded, the total luminosity of the remnant is provided by the release of energy from the natural decay of radioactive elements produced in the explosion.

Each element emits energy at some characteristic wavelengths as it decays, providing insight into the chemical composition of the supernova ejecta – the shells of material flung out by the exploding star.

Supernova 1987A, located in one of the Milky Way’s nearby satellite galaxies, the Large Magellanic Cloud, was close enough to be seen by the naked eye when its light first reached Earth in February 1987.

Ti-44 detection in SNR 1987A

During the peak of the explosion, fingerprints of elements from oxygen to calcium were detected, representing the outer layers of the ejecta.

Soon after, signatures of the material synthesised in the inner layers could be seen in the radioactive decay of nickel-56 to cobalt-56, and its subsequent decay to iron-56.

Now, thanks to more than 1000 hours of observation by Integral, high-energy X-rays from radioactive titanium-44 in supernova remnant 1987A have been detected for the first time.

“This is the first firm evidence of titanium-44 production in supernova 1987A and in an amount sufficient to have powered the remnant over the last 20 years,” says Sergei Grebenev from the Space Research Institute of the Russian Academy of Science in Moscow, and the first author of the paper reporting the results in Nature.

From their analysis of the data, the astronomers estimated that the total mass of titanium-44 that must have been produced just after the core collapse of SN1987A’s progenitor star amounted to 0.03% of the mass of our own Sun.

Searching for Ti-44

This value is near the upper boundary of theoretical predictions and is nearly twice the amount seen in supernova remnant Cas A, the only other remnant where titanium-44 has been detected.

“The high values of titanium-44 measured in Cas A and SNR1987A are likely produced in exceptional cases, favouring supernovae with an asymmetric geometry, and perhaps at the expense of the synthesis of heavier elements,” says Dr Grebenev.

“This is a unique scientific result obtained by Integral that represents a new constraint to be taken into account in future simulations for supernova explosions,” adds Chris Winkler, ESA’s Integral project scientist and co-author of the Nature paper.

“These observations are broadening our understanding of the processes involved during final stages of a massive star’s life.”

mardi 16 octobre 2012

Anyone in the world with a computer can contribute to research at CERN. Through the LHC@Home project, volunteers can offer up spare computing power to simulate and process collisions happening inside the Large Hadron Collider.

CERN LHC - To discover the secretsof the Universe

CERN recently improved the program with a new feature that helps scientists monitor the system that distributes work among volunteers’ computers. But the new feature is not the work of a CERN employee; it is the work of a college undergraduate who had the chance to work with CERN through the 2012 Google Summer of Code.

Note:

CERN, the European Organization for Nuclear Research, is one of the world’s largest and most respected centres for scientific research. Its business is fundamental physics, finding out what the Universe is made of and how it works. At CERN, the world’s largest and most complex scientific instruments are used to study the basic constituents of matter — the fundamental particles. By studying what happens when these particles collide, physicists learn about the laws of Nature.

The instruments used at CERN are particle accelerators and detectors. Accelerators boost beams of particles to high energies before they are made to collide with each other or with stationary targets. Detectors observe and record the results of these collisions.

Founded in 1954, the CERN Laboratory sits astride the Franco–Swiss border near Geneva. It was one of Europe’s first joint ventures and now has 20 Member States.

European astronomers have discovered a planet with about the mass of the Earth orbiting a star in the Alpha Centauri system — the nearest to Earth. It is also the lightest exoplanet ever discovered around a star like the Sun. The planet was detected using the HARPS instrument on the 3.6-metre telescope at ESO’s La Silla Observatory in Chile. The results will appear online in the journal Nature on 17 October 2012.

Alpha Centauri is one of the brightest stars in the southern skies and is the nearest stellar system to our Solar System — only 4.3 light-years away. It is actually a triple star — a system consisting of two stars similar to the Sun orbiting close to each other, designated Alpha Centauri A and B, and a more distant and faint red component known as Proxima Centauri [1]. Since the nineteenth century astronomers have speculated about planets orbiting these bodies, the closest possible abodes for life beyond the Solar System, but searches of increasing precision had revealed nothing. Until now.

Artist’s impression of the planet around Alpha Centauri B (Annotated)

“Our observations extended over more than four years using the HARPS instrument and have revealed a tiny, but real, signal from a planet orbiting Alpha Centauri B every 3.2 days,” says Xavier Dumusque (Geneva Observatory, Switzerland and Centro de Astrofisica da Universidade do Porto, Portugal), lead author of the paper. “It’s an extraordinary discovery and it has pushed our technique to the limit!”

The European team detected the planet by picking up the tiny wobbles in the motion of the star Alpha Centauri B created by the gravitational pull of the orbiting planet [2]. The effect is minute — it causes the star to move back and forth by no more than 51 centimetres per second (1.8 km/hour), about the speed of a baby crawling. This is the highest precision ever achieved using this method.

Alpha Centauri in the constellation of Centaurus (The Centaur)

Alpha Centauri B is very similar to the Sun but slightly smaller and less bright. The newly discovered planet, with a mass of a little more than that of the Earth [3], is orbiting about six million kilometres away from the star, much closer than Mercury is to the Sun in the Solar System. The orbit of the other bright component of the double star, Alpha Centauri A, keeps it hundreds of times further away, but it would still be a very brilliant object in the planet’s skies.

The bright star Alpha Centauri and its surroundings

The first exoplanet around a Sun-like star was found by the same team back in 1995 and since then there have been more than 800 confirmed discoveries, but most are much bigger than the Earth, and many are as big as Jupiter [4]. The challenge astronomers now face is to detect and characterise a planet of mass comparable to the Earth that is orbiting in the habitable zone [5] around another star. The first step has now been taken [6].

A journey to Alpha Centauri

“This is the first planet with a mass similar to Earth ever found around a star like the Sun. Its orbit is very close to its star and it must be much too hot for life as we know it,” adds Stéphane Udry (Geneva Observatory), a co-author of the paper and member of the team, “but it may well be just one planet in a system of several. Our other HARPS results, and new findings from Kepler, both show clearly that the majority of low-mass planets are found in such systems.”

“This result represents a major step towards the detection of a twin Earth in the immediate vicinity of the Sun. We live in exciting times!” concludes Xavier Dumusque.

A fly-through of the Alpha Centauri system

ESO will hold an online press conference offering journalists the opportunity to discuss the result and its impact with the scientists. To participate please read our media advisory.

Notes:

[1] The components of a multiple star are named by adding uppercase letters to the name of the star. Alpha Centauri A is the brightest component, Alpha Centauri B is the slightly fainter second star and Alpha Centauri C is the much fainter Proxima Centauri. Proxima Centauri is slightly closer to Earth than A or B and hence is formally the closest star.

[2] HARPS measures the radial velocity of a star — its speed towards or away from the Earth — with extraordinary precision. A planet in orbit around a star causes the star to regularly move towards and away from a distant observer on Earth. Due to the Doppler effect, this radial velocity change induces a shift of the star’s spectrum towards longer wavelengths as it moves away (called a redshift) and a blueshift (towards shorter wavelengths) as it approaches. This tiny shift of the star’s spectrum can be measured with a high-precision spectrograph such as HARPS and used to infer the presence of a planet.

[3] Using the radial velocity method, astronomers can only estimate a minimum mass for a planet as the mass estimate also depends on the tilt of the orbital plane relative to the line of sight, which is unknown. But, from a statistical point of view, this minimum mass is often close to the real mass of the planet.

[4] NASA’s Kepler mission has found 2300 candidate planets using an alternative method — searching for the slight drop in the brightness of a star as a planet passes in front of it (transits) and blocks some of the light. The majority of planet candidates detected by this transit method are very distant from us. But, in contrast, the planets found by HARPS are around stars close to the Sun — with the new discovery being the closest yet. This makes them better targets for many kinds of additional follow-up observations such as characterising the planet’s atmosphere.

[5] The habitable zone is a narrow annular region around a star in which water may be present in liquid form if conditions are right.

[6] ESPRESSO, the Echelle SPectrograph for Rocky Exoplanet and Stable Spectroscopic Observations, is to be installed on the ESO Very Large Telescope. Currently undergoing final design, it is scheduled to start operating in late-2016 or early-2017. ESPRESSO will feature radial velocity precision of 0.35 km/hour or less. For comparison, Earth induces a 0.32 km/hour radial velocity on the Sun. This resolution should thus enable ESPRESSO to discover Earth-mass planets in the habitable zone. The ESPRESSO consortium is led by team members responsible for the current discovery.

More information:

This research was presented in a paper “An Earth mass planet orbiting Alpha Centauri B”, to appear online in the journal Nature on 17 October 2012.

The year 2012 marks the 50th anniversary of the founding of the European Southern Observatory (ESO). ESO is the foremost intergovernmental astronomy organisation in Europe and the world’s most productive ground-based astronomical observatory by far. It is supported by 15 countries: Austria, Belgium, Brazil, the Czech Republic, Denmark, France, Finland, Germany, Italy, the Netherlands, Portugal, Spain, Sweden, Switzerland and the United Kingdom. ESO carries out an ambitious programme focused on the design, construction and operation of powerful ground-based observing facilities enabling astronomers to make important scientific discoveries. ESO also plays a leading role in promoting and organising cooperation in astronomical research. ESO operates three unique world-class observing sites in Chile: La Silla, Paranal and Chajnantor. At Paranal, ESO operates the Very Large Telescope, the world’s most advanced visible-light astronomical observatory and two survey telescopes. VISTA works in the infrared and is the world’s largest survey telescope and the VLT Survey Telescope is the largest telescope designed to exclusively survey the skies in visible light. ESO is the European partner of a revolutionary astronomical telescope ALMA, the largest astronomical project in existence. ESO is currently planning the 39-metre European Extremely Large optical/near-infrared Telescope, the E-ELT, which will become “the world’s biggest eye on the sky”.

A voluntary group of astronomers, using a website devoted to scientific astronomy, discovered an extrasolar planet orbiting four stars. This finding was subsequently confirmed by a second team of researchers.

Barely a year ago, astronomers were not sure that planets could exist in a binary system of stars, where two stars orbit each other. But after the discovery of circumbinary exoplanet, which would be two suns in the sky (much like the famous Star Wars Tatooine) scientists have realized that these worlds are possible and found at least five other similar systems.

About half of the stars in the universe are being a couple and if they can host planets then the chances of a life outside of our own world could be significantly increased.

The new exoplanet orbiting within a 4 star, named KIC 4862625, approximately 3200 light years from Earth. Scientists "citizens" Jek Kian San Francisco and Robert Gagliano Cottonwood, Arizona, have used the site Planethunters.org to analyze the data of these stars captured by the Kepler space telescope NASA and have noticed a decrease in their periodic light (transit).

The data showed that the planet passed in front of its parent star, a binary pair, every 138 days, eclipsing their light. The planet has been nicknamed PH1 (Planet Hunters 1) and should be a gas giant with a radius of 6.2 times that of the Earth, which makes it a little bigger than Neptune, with a mass of roughly half that of Jupiter. Binary stars are about 1.5 and 0.41 times the mass of the sun and they turn around with a period of 20 days.

The binary pairs of relatives PH1 in turn put into orbit by another binary pair of stars at a distance of 1000 times that between the Earth and the sun. If living beings could live on PH1, they do not just attend a double sunset, but they would also be able to identify two bright stars in their night sky, sailors among the stars.

The work has been confirmed by astronomers at Yale University. It was presented October 15 at the Division of the American Astronomical Society for Planetary Sciences in Reno, Nevada and the study was published in the Astrophysical Journal: Planet Hunters: A Transiting Planet in a Circumbinary Quadruple Star System: http://arxiv.org/abs/1210.3612

In addition, an independent analysis conducted by Veselin Kostov of Johns Hopkins University, also found evidence of an exoplanet is in quadruple star system. Independent confirmation of a result is an important part of the scientific process and this is one of the fastest to confirm the presence of this planet a bit exotic.

Kostov analysis corresponds very closely with the results of the Yale team, determining independently the mass and orbit of the exoplanet, despite having less data. The study will be published shortly on http://arxiv.org/.

Scientists using data from NASA's Wide-field Infrared Survey Explorer, or WISE, have uncovered new clues in the ongoing mystery of the Jovian Trojans -- asteroids that orbit the sun on the same path as Jupiter. Like racehorses, the asteroids travel in packs, with one group leading the way in front of the gas giant, and a second group trailing behind.

The observations are the first to get a detailed look at the Trojans' colors: both the leading and trailing packs are made up of predominantly dark, reddish rocks with a matte, non-reflecting surface. What's more, the data verify the previous suspicion that the leading pack of Trojans outnumbers the trailing bunch.

The new results offer clues in the puzzle of the asteroids' origins. Where did the Trojans come from? What are they made of? WISE has shown that the two packs of rocks are strikingly similar and do not harbor any "out-of-towners," or interlopers, from other parts of the solar system. The Trojans do not resemble the asteroids from the main belt between Mars and Jupiter, nor the Kuiper belt family of objects from the icier, outer regions near Pluto.

Image above: New results from NASA's Wide-field Infrared Explorer, or WISE, reveal that the Jovian Trojans -- asteroids that lap the sun in the same orbit as Jupiter -- are uniformly dark with a hint of burgundy color, and have matte surfaces that reflect little sunlight. Image credit: NASA/JPL-Caltech.

"Jupiter and Saturn are in calm, stable orbits today, but in their past, they rumbled around and disrupted any asteroids that were in orbit with these planets," said Tommy Grav, a WISE scientist from the Planetary Science Institute in Tucson, Ariz. "Later, Jupiter re-captured the Trojan asteroids, but we don't know where they came from. Our results suggest they may have been captured locally. If so, that's exciting because it means these asteroids could be made of primordial material from this particular part of the solar system, something we don't know much about." Grav is a member of the NEOWISE team, the asteroid-hunting portion of the WISE mission.

The first Trojan was discovered on Feb. 22, 1906, by German astronomer Max Wolf, who found the celestial object leading ahead of Jupiter. Christened "Achilles" by the astronomer, the roughly 220-mile-wide (350-kilometer-wide) chunk of space rock was the first of many asteroids detected to be traveling in front of the gas giant. Later, asteroids were also found trailing behind Jupiter. The asteroids were collectively named Trojans after a legend, in which Greek soldiers hid inside in a giant horse statue to launch a surprise attack on the Trojan people of the city of Troy.

"The two asteroid camps even have their own 'spy,'" said Grav. "After having discovered a handful of Trojans, astronomers decided to name the asteroid in the leading camp after the Greek heroes and the ones in the trailing after the heroes of Troy. But each of the camps already had an 'enemy' in their midst, with asteroid 'Hector' in the Greek camp and 'Patroclus' in the Trojan camp."

Before WISE, the main uncertainty defining the population of Jupiter Trojans was just how many individual chunks were in these clouds of space rock and ice leading Jupiter, and how many were trailing. It is believed that there are as many objects in these two swarms leading and trailing Jupiter as there are in the entirety of the main asteroid belt between Mars and Jupiter.

To put this and other theories to bed requires a well-coordinated, well-executed observational campaign. But there were many things in the way of accurate observations -- chiefly, Jupiter itself. The orientation of these Jovian asteroid clouds in the sky in the last few decades has been an impediment to observations. One cloud is predominantly in Earth's northern sky, while the other is in the southern, forcing ground-based optical surveys to use at least two different telescopes. The surveys generated results, but it was unclear whether a particular result was caused by the problems of having to observe the two clouds with different instruments, and at different times of the year.

Enter WISE, which roared into orbit on Dec. 14, 2009. The spacecraft's 16-inch (40-centimeter) telescope and infrared cameras scoured the entire sky looking for the glow of celestial heat sources. From January 2010 to February 2011, about 7,500 images were taken every day. The NEOWISE project used the data to catalogue more than 158,000 asteroids and comets throughout the solar system.

WISE space telescope in orbit. Image credit: NASA/JPL-Caltech

"By obtaining accurate diameter and surface reflectivity measurements on 1,750 Jupiter Trojans, we increased by an order of magnitude what we knew about these two gatherings of asteroids," said Grav. "With this information, we were able to more accurately than ever confirm there are indeed almost 40 percent more objects in the leading cloud."

Trying to understand the surface or interior of a Jovian Trojan is also difficult. The WISE suite of infrared detectors was sensitive to the thermal glow of the objects, unlike visible-light telescopes. This means WISE can provide better estimates of their surface reflectivity, or albedo, in addition to more details about their visible and infrared colors (in astronomy "colors" can refer to types of light beyond the visible spectrum).

"Seeing asteroids with WISE's many wavelengths is like the scene in 'The Wizard of Oz,' where Dorothy goes from her black-and-white world into the Technicolor land of Oz," said Amy Mainzer, the principal investigator of the NEOWISE project at NASA's Jet Propulsion Laboratory in Pasadena, Calif. "Because we can see farther into the infrared portion of the light spectrum, we can see more details of the asteroids' colors, or, in essence, more shades or hues."

The NEOWISE team has analyzed the colors of 400 Trojan asteroids so far, allowing many of these asteroids to be properly sorted according to asteroid classification schemes for the first time.

"We didn't see any ultra-red asteroids, typical of the main belt and Kuiper belt populations," said Grav. "Instead, we find a largely uniform population of what we call D-type asteroids, which are dark burgundy in color, with the rest being C- and P-type, which are more grey-bluish in color. More research is needed, but it's possible we are looking at the some of the oldest material known in the solar system."

Scientists have proposed a future space mission to the Jupiter Trojans that will gather the data needed to determine their age and origins.

The results were presented today at the 44th annual meeting of the Division for Planetary Sciences of the American Astronomical Society in Reno, Nev. Two studies detailing this research are accepted for publication in the Astrophysical Journal.

JPL manages, and operated, WISE for NASA's Science Mission Directorate. The spacecraft was put into hibernation mode in 2011, after it scanned the entire sky twice, completing its main objectives. Edward Wright is the principal investigator and is at UCLA. The mission was selected competitively under NASA's Explorers Program managed by the agency's Goddard Space Flight Center in Greenbelt, Md. The science instrument was built by the Space Dynamics Laboratory in Logan, Utah. The spacecraft was built by Ball Aerospace & Technologies Corp. in Boulder, Colo. Science operations and data processing take place at the Infrared Processing and Analysis Center at the California Institute of Technology in Pasadena. Caltech manages JPL for NASA. More information is online at http://www.nasa.gov/wise , http://wise.astro.ucla.edu and http://jpl.nasa.gov/wise .

This illustrated timeline features milestones in the journey of NASA's Cassini spacecraft. Scroll up to launch Cassini's voyage. Image credit: NASA/JPL.

Yesterday, NASA's / ESA's Cassini spacecraft celebrates 15 years of uninterrupted drive time, earning it a place among the ultimate interplanetary road warriors.

Since launching on Oct. 15, 1997, the spacecraft has logged more than 3.8 billion miles (6.1 billion kilometers) of exploration - enough to circle Earth more than 152,000 times. After flying by Venus twice, Earth, and then Jupiter on its way to Saturn, Cassini pulled into orbit around the ringed planet in 2004 and has been spending its last eight years weaving around Saturn, its glittering rings and intriguing moons.

And, lest it be accused of refusing to write home, Cassini has sent back some 444 gigabytes of scientific data so far, including more than 300,000 images. More than 2,500 reports have been published in scientific journals based on Cassini data, describing the discovery of the plume of water ice and organic particles spewing from the moon Enceladus; the first views of the hydrocarbon-filled lakes of Saturn's largest moon Titan; the atmospheric upheaval from a rare, monstrous storm on Saturn and many other curious phenomena.

"As Cassini conducts the most in-depth survey of a giant planet to date, the spacecraft has been flying the most complex gravity-assisted trajectory ever attempted," said Robert Mitchell, Cassini program manager at NASA's Jet Propulsion Laboratory in Pasadena, Calif. "Each flyby of Titan, for example, is like threading the eye of the needle. And we've done it 87 times so far, with accuracies generally within about one mile [1.6 kilometers], and all controlled from Earth about one billion miles [1.5 billion kilometers] away."

Round and Round Saturn

Graphic above: NASA's Cassini spacecraft has been on an epicroad trip, as this graphic of its orbits around the Saturn system shows. Image credit: NASA/JPL-Caltech/SSI.

The complexity comes in part from the spacecraft lining up visits to more than a dozen of Saturn's 60-plus moons and sometimes swinging up to get views of poles of the planet and moons. Cassini then works its way back to orbiting around Saturn's equator, while staying on track to hit its next targeted flyby. The turn-by-turn directions that mission planners write also have to factor in the gravitational influences of the moons and a limited fuel supply.

"I'm proud to say Cassini has accomplished all of this every year on-budget, with relatively few health issues," Mitchell said. "Cassini is entering middle age, with the associated signs of the passage of years, but it's doing remarkably well and doesn't require any major surgery."

The smooth, white paint of the high-gain antenna probably now feels rough to the touch, and some of the blankets around the body of the spacecraft are probably pitted with tiny holes from micrometeoroids. But Cassini still retains redundancy on its critical engineering systems, and the team expects it to return millions more bytes of scientific data as it continues to sniff, taste, watch and listen to the Saturn system.

And that's a good thing, because Cassini still has a daring, unique mission ahead of it. Spring has only recently begun to creep over the northern hemisphere of Saturn and its moons, so scientists are only beginning to understand the change wrought by the turning of the seasons. No other spacecraft has been able to observe such a transformation at a giant planet.

Starting in November 2016, Cassini will begin a series of orbits that wind it ever closer to Saturn. Those orbits kick off just outside Saturn's F ring, the outermost of the main rings. Then in April 2017, one final close encounter with Titan will put Cassini on a trajectory that will pass by Saturn inside its innermost ring, a whisper away from the top of Saturn's atmosphere. After 22 such close passes, the gravitational perturbation from one final distant Titan encounter will bring Cassini ever closer. On Sept. 15, 2017, after entry into Saturn's atmosphere, the spacecraft will be crushed and vaporized by the pressure and temperature of Saturn's final embrace to protect worlds like Enceladus and Titan, with liquid water oceans under their icy crusts that might harbor conditions for life.

"Cassini has many more miles to go before it sleeps, and many more questions that we scientists want answered," said Linda Spilker, Cassini project scientist at JPL. "In fact, its last orbits may be the most thrilling of all, because we'll be able to find out what it's like close in to the planet, with data that cannot be gathered any other way."

The Cassini-Huygens mission is a cooperative project of NASA, ESA and the Italian Space Agency. JPL manages the mission for NASA's Science Mission Directorate in Washington. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL. JPL is managed for NASA by the California Institute of Technology in Pasadena. For more information about the mission, visit: http://www.nasa.gov/cassini and http://saturn.jpl.nasa.gov and http://www.esa.int/SPECIALS/Cassini-Huygens/

lundi 15 octobre 2012

This week, ESA’s Integral space observatory celebrates ten years since launch on 17 October 2002. To mark the occasion, we present a slideshow of artist’s impressions depicting some of Integral’s most important discoveries.

Integral, short for International Gamma-Ray Astrophysics Laboratory, is equipped with two gamma-ray telescopes, an X-ray monitor and an optical camera. All four of Integral’s instruments point simultaneously at the same region of the sky to make complementary observations of high-energy sources.

Integral is often bathed in gamma-ray bursts, the death cries of massive stars that have burned up their fuel and exploded as a dramatic supernova, blasting high-energy radiation through the Solar System on a near-daily basis.

Integral science highlights

The satellite has also discovered objects that are much subtler than exploding stars. Highly absorbed X-ray binaries shrouded in material streaming off a high-mass companion star are too faint to be seen in optical and ultraviolet wavelengths, but high-energy X-ray and gamma-ray radiation can escape from that environment, detectable by Integral.

Meanwhile, supergiant fast X-ray transients display X-ray and gamma-ray outbursts that last only a few tens of minutes to hours. These objects comprise a neutron star – the dead core of a normal star which ended its life through a supernova – grabbing material from the clumpy wind emitted by its supergiant stellar neighbour.

A strange breed of pulsar with super-strong magnetic fields has also been uncovered by Integral. A pulsar is a rotating neutron star that appears to emit beams of radiation like a lighthouse.

Integral is also capable of all-sky surveys and has for the first time mapped the entire sky at the specific energy produced by the annihilation of electrons with their positron anti-particles.

The power released by the annihilating particles corresponds to over six thousand times the luminosity of our Sun.

Integral

Integral has also made the first unambiguous discovery of highly energetic X-rays coming from the galaxy cluster known as Ophiuchus. The emission is thought to originate from giant shockwaves rippling through the cluster’s gas as two galaxies collide and merge.

Integral has also been probing the feeding habits of active galaxies and black holes, which lurk in the bellies of most galaxies, including our own.

Many supermassive black holes are surrounded by thick dust discs, which Integral can peer through to identify the black hole hidden within.

Read more about Integral’s decade-long contribution to high-energy astrophysics in our special anniversary article coming up on Wednesday on ESA website.

dimanche 14 octobre 2012

The Austrian Felix Baumgartner jumped from 43 years on Sunday of over 39,000 meters and he crossed the sound barrier!

Red Bull Stratos - Felix Baumgartner jump Oct.14, 2012

He took up the challenge. The Austrian Felix Baumgartner broke the world record free-fall in the sky of New Mexico in the southwestern United States. According BFMTV and sponsor Rebull, the parachutist broke the sound barrier. Lequipe.fr for the Austrian has only approached the sound barrier with a speed of 1340 km/h.

Felix Baumgartner jumped from 43 years on Sunday of over 39,000 meters (Artist's view)

Felix Baumgartner was installed in a capsule attached to this ball made of very thin layers of plastic virtually transparent, ultra-light material for up to 36 000 meters, three times higher than a commercial airliner . The ascent of the balloon to the stratosphere lasted 2:30.

Felix Baumgartner breaking the sound barrier (Artist's view)

The skydiver Felix Baumgartner has passed the sound barrier in free fall. He ran his capsule attached to a helium balloon to 39,000 meters.

And the weather was appointment. Perfect weather we know, in the desert of New Mexico, "one or two days per week at this time of the year," according to the organizers of the event. Indeed, it is the wind that forced the adventurer to cancel Tuesday for the third time in the last minute, his attempt. The balloon was inflated and almost ready to leave when the wind strengthened, making the adventure too perilous.

Felix Baumgartner in the ascent capsule

20 minutes maximum descent

Once at 39,000 meters, Felix Baumgartner, with a pressure suit protecting a temperature of -68 ° C, opened the door of his cap and threw himself into space, plunging headfirst for more speed.

Felix Baumgartner jump. Screenshot redbullstratos.com.

The jump was broadcast live through more than 35 cameras on the ground and in the air, some attached to the combination of the parachutist.

The 43-year Austrian trains for five years for that jump. The greatest danger for him to lose control and start rotating on itself, resulting in a loss of knowledge that could cost him his life.

Felix Baumgartner landing. Screenshot redbullstratos.com.

The strength of the pressure suit is also essential. Any tear and sudden depressurization could boil the blood of the parachutist. "And I know that this experience will also help to build pressure suits even safer for pilots and space travelers," he said.

The record parachute freefall had been held since 1960 by a former colonel in the U.S. Air Force, Joe Kittinger, who, from a helium balloon, jumped from 31,333 m. The veteran of 83 years is also part of the team behind Red Bull Stratos Felix Baumgartner.

Red Bull Stratos seeks to advance scientific discoveries in aerospace for the benefit of mankind

Red Bull Stratos, a mission to the edge of space, will attempt to transcend human limits that have existed for 50 years. Supported by a team of experts Felix Baumgartner plans to ascend to 120,000 feet in a stratospheric balloon and make a freefall jump rushing toward earth at supersonic speeds before parachuting to the ground. His attempt to dare atmospheric limits holds the potential to provide valuable medical and scientific research data for future pioneers.

The Red Bull Stratos team brings together the world's leading minds in aerospace medicine, engineering, pressure suit development, capsule creation and balloon fabrication. It includes retired United States Air Force Colonel Joseph Kittinger, who holds three of the records Felix will strive to break.

Felix Baumgartner spacesuit

Joe's record jump from 102,800 ft in 1960 was during a time when no one knew if a human could survive a jump from the edge of space. Joe was a Captain in the U.S. Air Force and had already taken a balloon to 97,000 feet in Project ManHigh and survived a drogue mishap during a jump from 76,400 feet in Excelsior I. The Excelsior III mission was his 33rd parachute jump.

Although researching extremes was part of the program's goals, setting records wasn't the mission's purpose. Joe ascended in helium balloon launched from the back of a truck. He wore a pressurized suit on the way up in an open, unpressurized gondola. Scientific data captured from Joe's jump was shared with U.S. research personnel for development of the space program. Today Felix and his specialized team hope to take what was learned from Joe's jumps more than 50 years ago and press forward to test the edge of the human envelope.

Charting new possibilities in human flight, aerospace medicine, and high altitude escape systems

Red Bull Stratos medical director Dr. Jonathan Clark, who was the crew surgeon for six Space Shuttle flights, wants to explore the effects of acceleration to supersonic velocity on humans: "We'll be setting new standards for aviation. Never before has anyone reached the speed of sound without being in an aircraft. Red Bull Stratos is testing new equipment and developing the procedures for inhabiting such high altitudes as well as enduring such extreme acceleration. The aim is to improve the safety for space professionals as well as potential space tourists."